German patent 34 39 194 discloses a tubular accordion filter element having at its ends flexible end plates, made of a plastic molding compound, which form a truncated cone and are mounted in an annular shape around the filter element. The contact surface formed by the truncated cone extends to the filter element.
Furthermore, it is known from the German laid open publication 44 41 608 to seal off the end faces of the filter element with an elastic substance. This has the disadvantage that a mold is necessary for the elastic substance, as the filter element must be dipped into the mold and remain there until the elastic substance hardens. From EP-OS 0 724 472, an end piece is known made of irregularly placed fibers embedded in synthetic resin. In this case, one end of the filter is hermetically sealed.
An object of the present invention is to form the end pieces of an accordion filter element in a manner allowing their cost-effective production. Another object is to permit the securement of the accordion filter element to the carrier structure, which also provides a sealing function.